MD5 (Message-Digest Algorithm 5) is one of the most widely used cryptographic hash functions. It produces a 128-bit (16-byte) hash value, typically expressed as a 32-character hexadecimal number. While MD5 is no longer considered secure for cryptographic purposes, it remains popular for checksums and data integrity verification.
What is MD5?
MD5 (Message-Digest Algorithm 5) was designed by Ronald Rivest in 1991 as a successor to MD4. It's one of the most widely deployed hash functions and has been used extensively for file integrity verification, password storage, and digital signatures.
Key Features
- 128-bit Output: Produces a 32-character hexadecimal hash
- Fast Processing: Highly optimized for performance
- Four Rounds: Uses four rounds of 16 operations each
- HMAC Support: Widely used with HMAC for message authentication
- Checksum Verification: Popular for verifying file integrity
Common Uses
- File integrity verification (checksums)
- Password hashing (legacy systems)
- Digital signatures (legacy)
- Cache key generation
- Data deduplication
Security Note
MD5 is considered cryptographically broken due to collision vulnerabilities discovered in 2004. It should not be used for security-critical applications like SSL certificates or password hashing. For secure hashing, use SHA-256, SHA-3, or bcrypt/Argon2 for passwords.